Update ModelInterface.h
Update ModelInterface.h

Add the getExtendedSourceBoundaries function to get the limits of ra,dec, mainly for HAWC to decide the declination bands which matter.
giacomov/3ML,volodymyrss/3ML,giacomov/3ML,volodymyrss/3ML,sybenzvi/3ML,sybenzvi/3ML,sybenzvi/3ML